An endemic morning glory of southwestern New Mexico, Ipomoea gilana, known only from the Black Range of the Gila National Forest, is described and distinguished from a close phylogenetic associate, Ipomoea orizabensis (Ipomoea series Tyrianthinae), from mid-elevation mountains (800–2,000 m) of Mexico and Central America. The new species resembles I. lindheimeri (Ipomoea section Pharbitis) superficially, but molecular studies indicate closer relationships with I. orizabensis. Ipomoea gilana has slightly succulent leaf blades, nocturnal anthesis, light blue corollas, slightly exserted, subequal stamens with filaments inserted 2 cm above the base of the corolla tube and three-locular capsules. Ipomoea orizabensis s. l. has membranous leaf blades, diurnal anthesis, ruddy magenta corollas with unequal, included stamens inserted less than 1 cm from the base of the corolla tube and two-locular capsules. The new species is illustrated and a table of differences between the three species is provided.